NGC 7714/5 (Arp 284)

NGC 7714 is to the right (west) and NGC 7715 to the east.
The galaxies
are separated by 2 arcminutes (25 kiloparsecs).
Note the stellar bridge between the galaxies and
the tidal tails extending from both galaxies.
Also notice that NGC 7714 has a partial ring.
This image was obtained by
Beverly Smith with the 2.1m telescope
at
McDonald Observatory in collaboration with
Rick
Pogge (Ohio State University).

The distribution of interstellar atomic hydrogen
in this system looks like this:

To see a mpeg movie of a simulation of the NGC 7714 and NGC 7715 encounter,
click here (from
Smith and Wallin 1992,
Astrophysical Journal, vol. 393, p. 544).
In this model, the smaller galaxy has a mass of 1/3 that
of the larger galaxy and the impact parameter is 0.85 times
the radius of the larger disk.
Compare the
final frame with the McDonald optical image shown above.
Notice
that the ring, the bridge, and the tails are successfully reproduced.
This model only contains stars.